In container sterilization of low acid shelf stable products, the products are commonly processed in batches using controlled autoclaves commonly know as retorts. Agitation of products in a retort promotes accelerated sterilization, shorter cool times and improved product quality due to reduction of the thermal burden to the product. Product within the retort is typically loaded into a retort basket, which may take the form of a welded metal crate that houses the product that is in individual containers. The containers are collated in a specific pattern in the retort basket, clamped tightly and loaded into the retort chamber. The entire basket is then clamped. In an agitation-type retort this basket clamp is mechanically connected to a rod that is reciprocated back and forth in order to move the basket, and thus the product containers, back and forth.
Previously, the energy required to agitate the load in a reciprocating motion was accomplished through a drive mechanism consisting of a crankshaft mounted directly to single unbalanced flywheel mounted directly to a motor driven gear reducer. The gear reducer had a given speed range that was controlled by a variable frequency drive to modulate the hertz output to the motor. On small loads ranging from 0 to 200 pounds, this method was successful in providing the required torque, speed, and stroke to achieve desired product agitation results.
It would be desirable to provide a drive mechanism suited for moving larger loads (e.g., weights ranging from 600-2000 pounds) at 0 to 2 g acceleration range.